Recently, with respect to various types of equipment which include an open/close mechanism, there has been known an equipment in which a damper device is contiguously connected to an open/close shaft so as to attenuate or alleviate an impact which the equipment receives at the time of opening or closing the equipment. For example, in a warm water part cleaning device which is popularly used in view of the cleanliness and the hygiene thereof, a damper device is connected to an open/close shaft to alleviate an impact at the time of opening or closing a toilet lid, a toilet seat or the like.
As such a conventional damper device, there has been known the structure disclosed in Japanese Laid-open Patent Publication Hei5(1993)-296267.
That is, in the conventional damper device 200, as shown in FIG. 29, a columnar rotary shaft 203 is rotatably inserted in the inside of the hollow tubular cylinder 202, while a check valve 204 is formed between the cylinder 202 and the rotary shaft 204.
The cylinder 202 forms a pair of left and right partition walls 202a on an inner peripheral wall thereof in a state that the partition walls 202a project inwardly and, at the same time, the rotary shaft 203 is rotatably supported on distal end portions of the partition walls 202a. Oil is filled in an inner space 205.
The rotary shaft 203 forms wing portions 206 thereon in a state that the wing portions 206 project radially and, at the same time, check valves 204 are formed between distal end portions of the wing portions 206 and an inner peripheral wall of the cylinder 202. With the provision of these wing portions 206 and check valves 204, the inner space 205 of the cylinder 202 is divided into two chambers, that is, a pressure increasing chamber 205a which is formed on an front side with respect to the rotational direction of the rotary shaft 203 and a pressure reducing chamber 205a which is formed on a rear side with respect to the rotational direction of the rotary shaft 203.
The check valves 204 have outer portions thereof come into contact with an inner peripheral surface of the cylinder 202 and inner portions thereof surround the wing portions 206 of the rotary shaft 203. Due to such a constitution, a communication passage 207 which allows the pressure increasing chamber 205a and the pressure reducing chamber 205b to communicate with each other is formed between the inner portion and the wing portion 206, at the same time, a control port 208 is formed in the communication passage 207 on a pressure reducing chamber 205b side.
Here, in the drawing, numeral 209 indicates an O ring, numeral 210 indicates a cap which seals a distal end of the cylinder 202.
Then, in the damper device 200, when the rotary shaft 203 is rotated toward a front side, gaps between the wing portions 206 and the check valves 204 are eliminated and hence, a quantity of oil which flows into the pressure reducing chambers 205b from the pressure increasing chambers 205a is restricted by the check valves 204 whereby a rotational speed of the rotary shaft 203 is suppressed. On the other hand, when the rotary shaft 203 is rotated toward a rear side, gaps between the wing portions 206 and the check valves 204 assume a released state and hence, the quantity of oil is no more restricted whereby the rotary shaft 203 is smoothly rotated.
In this manner, the damper device 200 is configured such that when the rotary shaft 203 is rotated toward the front side, the check valves 204 are operated and hence, a large braking force is applied to the rotary shaft 203, while when the rotary shaft 203 is rotated toward the rear side, the check valves 204 are not operated and hence, a small braking force is applied to the rotary shaft 203.
The damper device 200 having the above-mentioned constitution is, as shown in FIG. 30, interposed between a cleaning device body 212 and a toilet seat 213 and a toilet lid 214 mounted on a toilet bowl.
Then, when a user merely lightly pushes the toilet seat 213 or the toilet lid 214 downwardly, the toilet seat 213 or the toilet lid 214 is gradually rotated downwardly due to an action of the damper device 200 whereby it is possible to preliminarily alleviate an impact which the toilet lid 213 or the toilet seat 214 receives upon impinging on a toilet bowl.
However, in the above-mentioned conventional damper device 200, since the check valves 204 are formed between the cylinder 202 and the rotary shaft 203, due to a size error on the cylinder 202 and the rotary shaft 203 caused during manufacturing, the cylinder 202 and the rotary shaft 203 are easily displaced from each other in the axial direction at the time of assembling the rotary shaft 203 into the cylinder 202 and hence, there exists a possibility that the individual difference (or irregularities) arises with respect to gaps between the bottom wall of the cylinder 202 and the wing portions 206.
When the individual difference arises with respect to gaps between the bottom wall of the cylinder 202 and the wing portions 206 at the time of manufacturing, a quantity of oil which flows into the pressure reducing chambers 205b from the pressure increasing chambers 205a through the gaps becomes different and hence, a braking force which is applied to the rotary shaft 203 by the damper device 200 becomes different for every damper device whereby it is difficult for the damper device 200 to obtain the stable quality and characteristics.
Further, since the check valves 204 are formed between the cylinder 202 which is not rotated and the rotary shaft 203 which is rotated, when the check valves 204 are operated so as to generate the braking force, the check valves 204 are strongly brought into contact with the cylinder 202 and hence, there exists a possibility that the check valves 204 are worn and broken thus giving rise to a drawback with respect to the durability of the damper device 200.